Morfologia e ecologia sensorial em aracnídeos troglóbios: perspectivas para a espeleobiologia brasileira

In this paper, we discuss some relationships between sensory ecology and the study of cave arachnids. As the ecology and behavior of a given species depends directly on which stimuli it responds to and that depends on the sensory structures it has, it is very important to understand morphological aspects of the animals. We therefore emphasize some of the troglomorphisms known in the group and address interesting questions to be further investigated. Studies on behavior may be more difficult to conduct because of the low number of troglobites typically found in caves, whereas studies on morphology are usually easier to carry out. We should also consider that natural and sexual selection may generate distinct predictions on what differences are to be found when comparing phylogenetically close epigean and troglobites. The various faunistic surveys carried out in Brazililian caves, combined with the literature listed in the present paper, are helpful for those interested in starting projects in this area.Neste texto nós discutimos as relações existentes entre a ecologia sensorial e o estudo de aracnídeos cavernícolas. Como a ecologia e comportamento de determinada espécie depende diretamente dos estímulos do ambiente aos quais ela responde e por sua vez isso depende das estruturas sensoriais que ela possui, é fundamental entender aspectos morfológicos dos animais. Ressaltamos, então, alguns dos troglomorfismos conhecidos no grupo e discutimos questões interessantes a serem investigadas. Trabalhos sobre comportamento de aracnídeos troglóbios podem ser mais difíceis de realizar devido a sua baixa abundância, enquanto estudos morfológicos tipicamente apresentam menos obstáculos. Deve-se levar em conta também que as teorias da seleção natural e sexual podem gerar previsões distintas sobre diferenças entre epígeos e troglóbios próximos filogeneticamente, o que traz importantes implicações sobre a compreensão da ecologia sensorial de determinada espécie. Os vários levantamentos de fauna cavernícola feitos no Brasil, combinados com a literatura elencada neste trabalho, auxiliam os interessados em iniciar projetos nesta área

Does Evolution matter?: a case study in Brazil of the effects of an evolutionary-thinking academic atmosphere in postgraduate students' belief in God/religious belief

Although the theory of evolution is more than 150 years old, a substantial proportion of the world population does not mention it when explaining the origin of human beings. The usual alternative conception is offered by creationism, one of the main obstacles to full acceptance of evolution in many countries. National polls have demonstrated that schooling and religiosity are negatively correlated, with scientists being one of the least religious professionals. Herein we analyzed both (1) the profile of 1st semester undergraduate students and (2), thesis and dissertations, concerning religious and evolutionary thoughts from Biology and Veterinary Schools at the largest university of South America. We have shown that students of Biology are biased towards evolution before they enter university and also that the presence of an evolutionary-thinking academic atmosphere influences the deism/religiosity beliefs of postgraduate students.Embora a teoria da evolução tenha mais de 150 anos, uma proporção substancial da população mundial não se refere a ela para explicar a origem dos seres humanos. A alternativa conceitual usual é oferecida pelo criacionismo, um dos principais obstáculos à aceitação plena da Evolução em muitos países. Pesquisas nacionais demonstraram que nível de instrução e religiosidade estão correlacionados negativamente, com os cientistas como sendo um dos profissionais menos religiosos. Aqui analisamos tanto (1) o perfil dos calouros do 1º semestre de 2011 como (2) as teses e as dissertações, com relação à expressão de concepções religiosas e evolutivas, das faculdades de Biologia e Veterinária da maior universidade da América do Sul. Demonstramos que os estudantes de Biologia tendem ao evolucionismo antes mesmo de entrar na universidade e que a presença de uma atmosfera acadêmica evolucionista influencia a expressão de deísmo/religiosidade entre os estudantes de pós-graduação

The effectiveness of post-contact defenses in a prey with no pre-contact detection

Most empirical and theoretical papers on prey–predator interactions are for animals with long-range detection, animals that can detect and react to predators long before these touch the prey. Heavy-bodied and chemically defended harvestmen (Arachnida, Opiliones) are an exception to this general pattern and rely on contact to detect arthropod predators. We examined the interactions between the Brazilian wandering spider Ctenus ornatus with harvestmen (Mischonyx cuspidatus) or control prey (Gryllus sp. and M. cuspidatus immature, both with soft integuments). Considering a prey–predator system in which fleeing from or reacting to a predator at a distance is not possible, we predicted both a high survival value of near-range defense mechanisms and that mortality would be higher in the absence of such defense mechanisms. We also expected the predator to behave differently when interacting with harvestmen or with a control prey without such defense mechanisms. Our results from laboratory experiments partially matched our predictions: First of all, histological sections showed that the integument of adult harvestmen is thicker than that of immature harvestmen and that of crickets. Adult harvestmen were less preyed upon than the control prey; the heavy armature increases the survival rate but the secretions from the scent glands do not. The predator did behave differently when attacking harvestmen compared to crickets. Despite the large size difference between predator and harvestmen, the protection provided by the armature allowed some of the harvestmen to survive encounters without pre-contact detection, thus greatly reducing the reliance on long-range detection to survive encounters with predators. Harvestmen call for theoretical and empirical work on prey–predator interactions that take into account the possibility that prey may not detect the predator before contact is established.FAPES

The effectiveness of post-contact defenses in a prey with no pre-contact detection

Most empirical and theoretical papers on prey–predator interactions are for animals with long-range detection, animals that can detect and react to predators long before these touch the prey. Heavy-bodied and chemically defended harvestmen (Arachnida, Opiliones) are an exception to this general pattern and rely on contact to detect arthropod predators. We examined the interactions between the Brazilian wandering spider Ctenus ornatus with harvestmen (Mischonyx cuspidatus) or control prey (Gryllus sp. and M. cuspidatus immature, both with soft integuments). Considering a prey–predator system in which fleeing from or reacting to a predator at a distance is not possible, we predicted both a high survival value of near-range defense mechanisms and that mortality would be higher in the absence of such defense mechanisms. We also expected the predator to behave differently when interacting with harvestmen or with a control prey without such defense mechanisms. Our results from laboratory experiments partially matched our predictions: First of all, histological sections showed that the integument of adult harvestmen is thicker than that of immature harvestmen and that of crickets. Adult harvestmen were less preyed upon than the control prey; the heavy armature increases the survival rate but the secretions from the scent glands do not. The predator did behave differently when attacking harvestmen compared to crickets. Despite the large size difference between predator and harvestmen, the protection provided by the armature allowed some of the harvestmen to survive encounters without pre-contact detection, thus greatly reducing the reliance on long-range detection to survive encounters with predators. Harvestmen call for theoretical and empirical work on prey–predator interactions that take into account the possibility that prey may not detect the predator before contact is established.FAPES

Gregarious behavior of two species of Neotropical harvestmen (Arachnida: Opiliones: Gonyleptidae)

We present the first record and description of the gregarious behavior of the Neotropical harvestmen Serracutisoma proximum (Mello-Leitao 1922) and Serracutisoma spelaeum (Mello-Leitao 1933) (Opiliones: Gonyleptidae: Goniosomatinae) (DaSilva & Gnaspini 2010). We followed and described the pattern of these aggregations over a period of 17 months in a cave in southeastern Brazil. Individuals of the two species aggregated with both conspecifics and heterospecifics during the non-reproductive season (i.e., from October to March, the cool and dry season). Aggregations contained up to 81 individuals, usually with a female-biased adult sex ratio. Multispecific aggregations were usually composed mainly of representatives of one of the two species, suggesting that although these species also aggregate with heterospecifics, there is a preference for aggregating with conspecifics. This study provides novel information on the social behavior of harvestmen, specifically regarding the composition of multispecific aggregations.FAPESP [04/04290-4, 00/04686-4]FAPESPCNPqCNPq [301839/2004-2